Filter leaf



P. S. SCHUHMANN Jan. 29,; r1924 FILTER LEAF Filed Apri 19 LA ATTORNEYY fil l up. At that time the isfil'led with liquid andwhen the liquid is frfames when pressure in which the vliquid ,bulges the cloth. This Patented Jan. ze, v1924.

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Application med Api-n 19, 11923. seriaim. essere.

To all whom t may com/'emr Be it known that I, PETER SHERB SCHH- MANN, a citizen f the United States residing at Woodhaven, in the county of Queens,

State of .N ew York, have invented certain new and useful Improvements in Filter Leaves; and I ing to be a full, clear, and exact of the invention, skilled in the art to which it appertains to make and use the same.`

his invention relates to filtering apparatus and particularly to filters of the 4leaf type in whichgliquid is carried through a ter mediumat the surface of the'leaf by pressure or suction. f

Such filters usually com rise a plurality of leaves, eaeh consisting of) a suitable frame or support and a filter cloth stitched over the frame. The leaves receptacle which may be closed or open and to be filtered is held. In .operating filters of the type described, 4the pressure or suction is withdrawn when a cake of sufiicient thickness has been built space within'each leaf description drained from the receptacle the liquid within the leaf seeps through the filter cloth, exerting, at the same time, a pressure which causes thecake to slide and break and prevents uniform washing. To prevent bulging of the filter cloths, it' hasbeen necessary eretofore to insert fastenings, called grommets, through the cloth and frames.k Moreover, the liquid being filtered mixes with the wash water Vin greater proportion than is desirable; thus introducix; lossesI in efficiency which cannot be avide with filter leaves as heretofore known.

resent invention to It is the object of the -filtersby avoiding increase the efiioiency o through the filter cloth with the wash water and by preventing the cloth from bulging.

other object of the invention is to simplify the lter'leave's by eliminating grommets and to provide self-draining filter leaves which permit the esc'apeof liquid from the drawn. y Further objects and advantages of the in- A vention will be apparent" as it isabetter understoodby reference to the following specido 'hereby declare the followsuch as will enable others4 are supported in awhich has passed or suction is with fication and accompanying drawing, in which Fig. 1 is a View of the assembled lilter leaves;

F ig. '2 is a side elevation of a filterleaf embodying 'the invention;

Fig. 3 is a transverse section through the filter leaf; and

fFigs. 4' and 5 are enlarged sectional details o indicating the operation thereof.

In carrying out the invention filter leaves*y of any kind may be used, the frames and filter cloth being such las is best adapted to the handling of any iven material. The leaves may be supporte in open or closed receptacles and the liquid may be passed through the filter cloth by suctionv or pressure as vis preferred. In a common type of filter to which the invention has been applied, the leaves are supported in' a cylindrical closed tank, the bottom of which may Swing down- Wardly to permit discharge of the cake. A pressure inlet permits the introduction of liquids with suspended solids into the tank and the filter leaves are connected to an outlet through which the filtered liquid escapes.

Each leaf comprises a frame or support and a cloth bag which completely encloses the fra-me. The frame is circular and th'e cloth is sewed in place thereon to provide two oppositely disposed faces through which the liquid passes. Instead of closing the bag as is usual, itis, according to the present invention, provided with a downwardly ex'- tending neck which is open at the bottom. The cloth forming the neck is sewed at the opposite edges thereof and the normal tendency of the cloth is to remain in-contact.

en pressure or suction is exerted to operate the filter, the opposite sides of the neck remain closely-in contact and the assage between the two sides of the nec is closed. tightly to prevent passage of liquid containing suspended solids therethrough. When the pressure or suction is released and the liquid is drained' from the tank, the weight of liquid in the leaf causes the o positesides of the neck to spread and thus permit the. liquid to return freely -to the tank. The neck consequently forms an automatic valve which prevents the passage of liquidinto the leaf but permits escape of .liqlliid therefrom.

the valve at the bottom of the filter leaf tank or receptacle having a pressure inlet 6 rfor the liquid carrying suspended particles and a drainoutlet 7. A plurality of leaves are supported in the tank 5, each of which may consist of a frame 8 and acovering 9 of filter cloth. Each leaf is provided with an "outlet 10 through which the filtered liquid escapes, these outlets being yconnected to a header (not shown). This arrangement perl the required thickness,

lmitsvtlie introduction of liquid containing solids in suspension pto the tank and the Withdrawal of filtered liquid. In operation, When the cake has built up on the leaves to ressure is released and the tank is drained t rough At the bottom of each filter bag a neck 11 is formed by sewing together the edgesof extenons of the filter cloths. As shown in Figs-3 and 4 the end of the neck, is open. Vhile pressure remains -on the liquid in the .tank the neck is closed as shown in Fig. 3,

but when pressure is released theweight of liquid in the leaf opens the neck as shown in Fig. 4 and the liquid drains readily from the leaf. When Water is` introduced to Wash the cake, the-neck closes, and when the wash Water is discharged from the tank the leaf is again drained through theA open neck.

'The advantages of the invention are simplification of the filter leaf, no lgrommets being used, and increased efficiency because the cake does notslide and fall and the fil'- tered liquid `does not kmix With the Wash Water. Washing is more rapid and certain,

and loss of solids in the Wash Water is reduced to a minimum.' The filter cloth is free throughout its areaand it can flap back 'and' forth Without bulging. This keeps the pores of the cloth free from solids` and increases its life.

the outlet 7.

Various changes may be made in the details of arrangement ofthe filter and in the means employed to prevent escape of liquid from the leaf Without departing from the invention .or sacrificing any of theadvantages thereof.

I claim 1. In a filter, a leaf comprising a frame, a

medium and to -permit the escape of liquid i therefrom When the filterv is drained, vsaid means comprising a valve at the bottom of the leaf.

3. In a filter, a leaf comprising a frame,

a filter medium supported thereon, meansl automatically oper-ating to prevent entrance of liquid to the leaf except through the filter medium and to permit the escape of liquid therefrom When'V the filter is drained, said means comprising a valve at the bottom of the leaf consisting of Aextensions of the filter medium secured at the edges and open at the bottom.

4. In aV filter, a leaf comprising a frame and a bag of filter cloth surrounding the3 frame 'and having an open neck at the bottom Whchis adapted to close vwhen the filter is filled with liquidand to open when the filter is drained.

In testimony whereof I ailix my signature. i

PETER SHERB SCHUHMANN. 

